The present invention relates to a plasma treatment method and a method of manufacturing a semiconductor device, and particularly to a plasma treatment method for treating a surface of an insulation film and a method of manufacturing a semiconductor device by applying the plasma treatment method.
In recent years, attendant on the increase in the degree of integration of semiconductor integrated circuit devices (LSI), the wiring process technology has been becoming more and more important in relation to high-speed operations of the LSI. This is because it has come to be conspicuous that the wiring delay time is greater than the gate delay time due to the miniaturization of semiconductor devices.
For suppressing the wiring delay time, it may be necessary to reduce the capacitance between wirings or to lower the wiring resistance. In addition, since the miniaturization of semiconductor devices is attended by an increase in current density, an enhanced countermeasure against electro migration (EM) may also be needed. Then, it is considered that, for meeting these requirements, it is important to introduce of a multi-layer wiring technology in which a copper (Cu) wiring and a low dielectric constant layer insulation film are used.
The Cu wiring shows an electric resistance of about ⅔ times that of an aluminum alloy wiring according to the system in related art. Therefore, Cu is a material with which a reduction in wiring resistance can be realized. In addition, Cu is a material which promises a higher electro migration durability than that of the Al alloy wiring. Therefore, introduction of the Cu wiring into practical products has already begun.
As a method for forming a Cu wiring, the Damascene process is generally used. A method of forming a Cu wiring by use of the Damascene process will be described below. First, a trench is formed in a layer insulation film such as an SiO2 film by application of a photolithography technique and an etching technique. Thereafter, an opening portion is formed in a stopper layer for connection between a lower-layer wiring and a contact. Then, a barrier metal film for preventing diffusion of Cu into the inside of the layer insulation film inclusive of the inside of the trench is formed, in the manner of filling up the trench with Cu. Thereafter, the surplus Cu film on the layer insulation film is removed by use of a CMP (Chemical Mechanical Polishing) process or the like. As a result, the Cu wiring by use of the Damascene process is completed.
In order to reduce the capacitance between wirings in the Cu wiring as above-mentioned, an SiOCH film, an SiOF film, organic insulation films and the like which are lower in dielectric constant than a silicon oxide (SiO2) film have been being developed and put to practical use as a layer insulation film.
The low dielectric constant film as above can be obtained by lowering the polarizability of the material, but the use of only the lowering of polarizability has a limit. In view of this, it is considered to be necessary to lower the dielectric constant by making the film porous in structure. Recently, attention has been paid to the development of a low dielectric constant film obtained by making porous a film of a low dielectric constant material.